Sewing device with a double chain stitch sewing machine



1969 H. SCHOLL ET-AL 3,461,826

SEWING DEVICE WITH A DOUBLE CHAIN STITCH SEWING MACHINE Filed Feb. 20,1968 mm H INVENTORS.

flfl/YS 3CHOLL) flLF/QL D HF/MA/ IV I United States Patent 3,461,826SEWING DEVICE WITH A DOUBLE CHAIN STITCH SEWING MACHINE Hans Scholl,Bielefeld, and Alfred Heimann, Senne, Germany, assignors to KochsAdlerrlahmaschinen Werke AG, Bielefeld, Germany .9 Filed Feb. 20, 1968,Ser. No. 706,960

Int. Cl. D05b 1/10 US. Cl. 112-121.11 5 Claims ABSTRACT OF THEDISCLOSURE A pattern controlled sewing device having workpiece clampingholders and guide patterns arranged beneath the clamping holders. Adouble chain stitch sewing machine is provided with a thread carryingneedle, a thread carrying looper, a throat plate with an inset pivotedin it and having an oblong stitch hole, and a thread spreader to allowthe forming of seams in every feed direction. The inset is controlled bya pattern follower device cooperating with the patterns and in drivingconnection with the inset through transmitting means in the form of anendless ball string, for rotating the oblong stitch hole in a directioncorresponding to the shape of the patterns.

It is a primary object of this invention to provide an automatic sewingdevice for producing collars, cuffs or workpieces with changingdirection of the seam by means of a double chain stitch sewing machinewhich has a thread carrying needle, a thread carrying looper, aworkpiece press pad and a thread spreader, which allow the forming of aseam corresponding to the shape of the pattern used in the sewingdevice, in order to avoid the replacement of the lower threadbobbin,'which is necessary when using a lockstitch sewing machine aftersewing a fixed length of a seam.

It is a further object of this invention to provide a pattern controlledautomatic sewing device as described in the United States patent to HansScholl No. 3,276,405, dated Oct. 4, 1966. This patent discloses patternsfor producing the above described articles and a driven roller or amagnetic roller for the cooperation of the pattern with a double chainstitch sewing machine provided with the above described means.

It is already known to develop double chain stitch sewing machines insuch a manner that they sew in every desired direction. For this purposea circular motion is imparted to the thread spreader above the threadcarrying looper. During these motions the thread spreader moves forwardwith the looper and catches the looper thread, as well as the needlethread loop hanging on the looper between the looper point and thestitch hole. When returning, the thread spreader leading the looper,deflects the looper thread and the needle thread loop in such a manneras to form a thread triangle for the entering of the needle. The jointsof the thread triangle are always fixed in the same position by thelooper, the thread spreader and the stitch hole, irrespective of thedirection and length of the feeding.

Such an arrangement is disclosed in German Patent No. 483,989, patentedon Oct. 2, 1925.

As with chainstitch sewing machines, the loop of the needle thread isonly tightened at the next entrance of the needle, the stitch hole ofthese sewing machines being developed in sewing direction as an oblonghole. Such a stitch hole however allows the forming of a seam only inone or two feed directions, even if the sewing machine is equipped withsewing tools, which enable sewing in all directions. In order to be ableto sew with the double chainstitch sewing machine in all directions,according to 3,461,826 Patented Aug. 19, 1969 "ice the above mentionedpatent, it has been proposed to provide the upper surface of the throatplate around the siitch hole with a hollow. However, this isobjectionable, since this fabric is drawn down to the bottom of thestitch hole by the needle while sewing, thus hindering an eventightening of the threads.

In order to overcome this shortcoming, there has been proposed a throatplate having three or more slots formed therein and extending from thestitch hole in star-shaped relation thereto. It should thus be possibleto lay down the needle threads in one of these slots, so as to achievean unobjectionable tightening of the threads, when fixing the stitches.Such an arrangement is disclosed in the US. Patent 3,313,259, issued onApr. 11, 1967.

However it is possible when feeding the workpiece in certain directions,that the threads will not slip off from the rounded ends of the armsinto the slots, thus producing false stitches. The throat plateaccording to this patent is not suitable for automatic sewing devices inwhich the workpieces are clamped into clamping holders.

Summary According to the invention, the above problems are solved byproviding a throat plate inset pivoted in the throat plate, which iscontrolled by a pattern-follower device through transmitting means insuch a manner that the oblong stitch hole will be aligned according tothe shape of the patterns. The pattern follower device consists of agauge finger secured to a lever which is pivoted on the driving shaft ofthe roller or magnetic roller and of a torsion spring which presses thegauge finger against the guiding patterns, furthermore of a drivingwheel fastened to the lever for transmitting the rotary motions of thegauge finger to the throat plate inset through the transmitting means.

The inset pivoted in the throat plate is provided with a U-shaped seatfor the workpieces, whereby this seat encloses partially the stitchhole, and is provided with teeth on its circumference. An idler gearmating with the teeth of the inset and a further gear wheel also matingwi-h the idler gear are pivoted in the throat plate, whereby the gearwheel is fastened to a driven wheel which is in driving connection withthe pattern-follower device through the transmitting means.

The transmitting means consists of an endless ball string, which isguided over guide pulleys pivoted on the sewing machine.

Brief description of the drawings FIG. 1 is a partial diagrammatic topplan view of a device for the automatic joining of workpieces by meansof a double chain stitch sewing machine mounted on an arm, whereby thesewing machine is controlled by guiding patterns, and which ShOWs thepattern-follower device aligning the stitch hole;

FIG. 2 is a" section through the pattern-follower device on an enlargedscale;

FIG. 3 is a top plan view on the throat plate with the inset pivotedtherein and driven by gear wheels.

Description of the preferred embodiment On an arm or hinged arm 1(FIG. 1) of a device shown and described in U .8. Patent No. 3,276,405,for automatic sewing of workpieces 2 clamped in workpiece holders 3,there is secured a double chain stitch sewing machine 5, provided with afabric carrier arm 4. The sewing machine 5 has a thread carrying needle6, a workpiece presser pad 7 and is provided with a thread carryinglooper and a thread spreader, which allows a formation of a scam inevery possible feed direction.

A driven roller or magnetic roller 8 is supported in the arm or hingedarm 1 and is disposed coaxially with the needle 6. The roller ormagnetic roller 8 coacts with a guiding pattern 9, mounted below theworkpiece holder 3. On the driving shaft 10 for the roller or magneticroller 8 there is provided a pattern-follower device 11. It consists ofa lever 12 provided with a gauge finger 13, the lever 12 being securedto a bushing 14, pivoted on the driving shaft 10. Secured to the bushing14 is a driving wheel 15 for a transmitting means 16 in the form of anendless ball string 17. The pattern-follower device 11 is under thetension of a torsion spring 18, which presses the gauge finger 13against the guiding pattern 9 (FIG. 1).

The ball string 17 is guided over guide pulleys 19, pivoted on jibs 20,21, and transmits the movements of the lever 12 to a driven wheel 22(FIG. 1 and 3) which is arranged below the throat plate 23 and connectedwith a gear wheel 24 pivoted within the throat plate 23 (FIG. 3). Withthis gear wheel 24 mates an idler gear 25 likewise pivoted in the throatplate 23 and which mates with the teeth 26 of a throat plate inset 27which is provided with an oblong stitch hole 28 for the needle 6. Thethroat plate inset 27 is provided with a U-shaped seat 29 for theworkpiece 2, while the seat 29 encloses partially the stitch hole 28.

The arm or hinged arm 1 carrying the sewing machine 5, is guided alongthe outline of the pattern 9 (FIG. 1) in the direction of the arrow A bythe driven roller or magnetic roller 8, whereby the needle 6 and thestitch forming tools produce a seam in the workpiece 2 corresponding tothe shape of the pattern 9. The throat plate inset 27 is controlled bythe pattern-follower device 11 over the transmitting means 16 and thegears 24, 25 in such a manner, that the oblong stitch hole 28 is alignedin the direction of the seam in order that it may form a satisfactorydouble chain stitch seam.

We claim:

1. In a sewing device, a double chain stitch sewing machine having afabric carrier arm, a thread carrying needle, a thread carrying looper,a spreader, for forming seams in every feed direction; a workpiece presspad and a throat plate provided with an inset having an oblong stitchhole, said inset being pivoted in said throat plate and rotatable aboutthe axis of said needle, a hinged arm articulated to said sewing device,said fabric carrier arm being arranged on said hinged arm, workpieceholders secured to said machine, guiding patterns mounted below saidworkpiece holders, a driven magnetic roller coacting with said guidingpatterns and mounted in said hinged arm, the axis of said needle beingin alignment with the axis of said magnetic roller, pattern-followermeans for controlling said inset, transmitting means for saidpatternfollower means whereby the oblong stitch hole in said inset willbe aligned according to the shape of said guiding patterns.

2. In a sewing device as claimed in claim 1, wherein saidpattern-follower means includes a driving shaft for said roller, a leverpivoted on said shaft, a gauge finger secured to said shaft, a torsionspring pressing said finger against the guiding patterns, a drivingwheel secured to said lever for transmitting the rotary motions of saidgauge finger to said throat plate inset through said transmitting means.

3, In a Sewing device as claimed in claim 1, wherein said inset pivotedin said throat plate is provided with a U-shaped seat for saidworkpieces, said seat enclosing partially said stitch hole and beingprovided with teeth on its circumference, an idler gear mating with theteeth of said inset, a gear wheel mating with said idler gear andpivoted in said throat plate, a driven wheel in driving connection withsaid pattern-follower device through said transmitting means, said gearwheel being secured to said driven wheel.

4. In a sewing device as claimed in claim 1, wherein said transmittingmeans consists of an endless ball string, and guide pulleys pivoted onsaid sewing machine, said endless ball string being guided over saidguide pulleys.

5. In a sewing device. having a double chain stitch sewing machineprovided with a fabric carrier arm, a thread carrying needle, a threadcarrying looper, a spreader for forming seams in every feed direction; aworkpiece press pad and a throat plate provided with an inset having anoblong stitch hole; said inset being pivoted in said throat plate androtated about the axis of said needle, said fabric carrier arm beingarranged on said arm of said sewing device, workpiece holders mounted onsaid arm, guiding patterns mounted below said workpiece holders, adriven roller coacting with said guiding patterns mounted in said arm,the axis of said needle being aligned with the axis of said roller,throat plate inset transmitting means for transmitting movement to saidinset from said guiding patterns for aligning the oblong stitch hole insaid inset according to the shape of said patterns, saidpattern-follower consisting of a driving shaft for said roller, a leverpivoted on said driving shaft, a gauge finger secured to said lever, atorsion spring pressing said gauge finger against said guiding patterns,a driving wheel fastened to said lever for transmitting the rotarymotions of said gauge finger to said throat plate inset transmittingmeans therefor, said inset being provided with a -U-shaped seat for saidworkpieces, said seat enclosing partially said stitch hole and havingteeth on its circumference, an idler gear mating with the teeth of saidinset and a gear wheel mating with said idler gear, said gear wheelbeing pivoted in said throat plate, a driven wheel in driving connectionwith said pattern-follower device, said transmitting means consisting ofan endless ball string guided over guide pulleys pivoted on said sewingmachine, said gear wheel being secured to said driven wheel.

References Cited UNITED STATES PATENTS 6,181,50 12/1926 France.

JAMES R. BOLER, Primary Examiner U.S. Cl. X.R.

